The present invention relates in general to improvements in a paper feeding apparatus for a printer for feeding individual sheets of paper from a paper stacker or storage tray toward a printing assembly, and more particularly to improvements associated with the paper stacker for easy loading of a stack of paper on the stacker and stable, smooth feeding of sheets of various thicknesses.
A paper feeding apparatus is known in the art, which comprises a frame secured to a typewriter or printer, feed rollers supported on the frame rotatably to feed individual sheets of paper, a paper stacker supported by the frame movably relative to the feed rollers and holding the sheets of paper in a stack, and biasing means for biasing the paper stacker to urge the top of the paper stack into contact with the feed rollers. In such paper feeding apparatus, the sheets of paper are fed from the stacker one after another with the rotating feed rollers kept in frictional contact with the top sheet of the paper stack on the stacker by the biasing means. Upon re-loading the stacker with a new stack of paper, it is generally required to move the stacker to its retracted position against an urging force of the biasing means, re-load the stacker and return the stacker to its normal advanced position at which the top sheet of the paper stack is urged against the feed rollers. To this end, it has been attempted to provide such known feeding apparatus with means for locking the paper stacker at its retracted position. However, such means is not simple in construction and operation for moving the stacker against the resiliency of the biasing means and unlocking the stacker after it has been re-loaded with a new stack of paper. Thus, there has been a need of providing a paper feeding apparatus for a printer with simplified latch and unlatch means for moving its paper stacker to its retracted position, holding the stacker at the same position and releasing the newly loaded stacker, which means is easily operable by a wide variety of users who are familiarized in varying degrees with the printer.
In the meantime, it is recognized that a paper stacker is required to accommodate various kinds of sheets, e.g., sheets of different thicknesses. In this respect, the known paper feeding apparatus as previously described has another problem that its action of feeding one sheet at a time is not stable for all thicknesses of paper that are stored in the stacker. More specifically, when the stacker is loaded with thin sheets of paper the feed rollers tend to feed two or more sheets at one time. Conversely, the feed rollers are likely to fail in feeding a sheet in correct manner when the paper is comparatively thick.